Adds support for mutually recursive functions (#181)

See issue in [hoest/sublimetext-fsharp#13 which depends on this project and has more info.

grammars/fsharp.json

@@ -927,7 +927,7 @@
             "patterns": [
                 {
                     "name": "binding.fsharp",
-                    "begin": "\\b(let mutable|static let mutable|static let|let inline|let|member val|static member inline|static member|default|member|override|let!)(\\s+rec|mutable)?(\\s+\\[\\<.*\\>\\])?\\s*(private|internal|public)?\\s+(\\[[^-=]*\\]|[_[:alpha:]]([_[:alpha:]0-9\\._]+)*|``[_[:alpha:]]([_[:alpha:]0-9\\._`\\s]+|(?<=,)\\s)*)?",
+                    "begin": "\\b(let mutable|static let mutable|static let|let inline|let|and|member val|static member inline|static member|default|member|override|let!)(\\s+rec|mutable)?(\\s+\\[\\<.*\\>\\])?\\s*(private|internal|public)?\\s+(\\[[^-=]*\\]|[_[:alpha:]]([_[:alpha:]0-9\\._]+)*|``[_[:alpha:]]([_[:alpha:]0-9\\._`\\s]+|(?<=,)\\s)*)?",
                     "end": "\\s*(with\\b|=|\\n+=|(?<=\\=))",
                     "beginCaptures": {
                         "1": {